With the shortage of RPi4's, I've been exploring the use of relatively cheap (but not as cheap!) x86 alternatives.  I 
have a LattePanda board that I can boot up fine from USB and can use the nvme driver to access external storage, but I'd
 like to take advantage of the sdmmc/emmc that's on board.  Problem is I can't seem to get the devb-sdmmc to recognize 
either the SD reader or the eMMC.  

pci-tools -v show what I think are the controllers?

B000:D28:F00 @ idx 18
        vid/did: 8086/31cc
                Intel Corporation, <device id - unknown>
        class/subclass/reg: 08/05/01
                SD Host Controller Base Systems Peripheral

B000:D30:F00 @ idx 19
        vid/did: 8086/31d0
                Intel Corporation, <device id - unknown>
        class/subclass/reg: 08/05/01
                SD Host Controller Base Systems Peripheral

But my attempts to form the correct devb-sdmmc command line have not succeeded.  Any suggestions?

Thanks!
David